1. Field of the Invention
The present invention relates to a method of resolution using a measurement system arranged on an articulated or non-articulated structure with a view to capturing the movements thereof. In the event that this structure is a person or an animal, it can be applied, for example, to the fields of medicine, movie animation, sports or video games.
2. Description of the Related Art
Since its first fields of application, which are medicine and movie animation, the capture of the movement of a whole human body is a technique that is rapidly expanding, which has seen its use become widespread, notably in sport and video games. Indeed, the democratization of microelectromechanical systems, better known under the English acronym MEMS, notably the democratization of inertial and magnetic sensors such as accelerometers, magnetometers and gyroscopes, has enabled the spread of very compact devices called ‘attitude units’ which are capable of assessing their own orientation with respect to a terrestrial reference frame. There are various types of attitude units according to the sensors that they combine. However, in the prior art, only the combination of an accelerometer with a magnetometer and a gyroscope in an attitude unit can be used for estimating the kinematic orientation of said unit satisfactorily in the presence of unknown acceleration, i.e. without any a priori knowledge about its movement or in the presence of magnetostatic interference. Indeed, the orientation of the unit with a non-zero proper acceleration of said unit can only be estimated in the case of a data fusion with three modalities called AGM (Accelerometers, Magnetometers and Gyroscopes) fusion. In the case of a fusion with two modalities called AM (Accelerometers and Magnetometers) fusion, kinematic orientation cannot be estimated, since the acceleration and gravitation information contained in the accelerometer measurement are inseparable.
Thus, a solution for capturing kinematic movement of the whole body called Moven has been developed by the company Xsens. This solution is described in a document entitled Inertial Sensing Of Human Movement (H. J. Luinge). It is based on attitude units known under the trade name MTx. Each MTx combines a triaxial accelerometer with a triaxial magnetometer and a triaxial gyroscope, thus providing the orientation and displacement of the segment of the body on which it is fixed, whether this is the shoulder, the arm or the forearm, for example. Then the segments are associated in keeping with the skeleton. Seventeen MTxs are thus judiciously distributed in a combination in order to ensure their position on the body. The MTxs are connected by wired connections to two electronic packages responsible for collecting and synchronizing the data from the MTxs. The Xbus Masters communicate with a computer through a wired or wireless connection. Unfortunately, attitude units such as the MTxs, which combine an accelerometer with a magnetometer and a gyroscope, have a fairly high energy consumption. MTxs are especially expensive, which may not be economically justified in some fields. These are drawbacks that the present invention intends to address.
The French patent application FR 2 916 069 A1 describes another solution for capturing the kinematic movements of the whole body from a toolbox called HuMAnS according to the English acronym for Humanoid Motion Analysis and Simulation. This is a set of tools in the C language and Scilab developed by one of the applicants in collaboration with INRIA. Unlike the Moven solution cited previously, which is linked to MTx units, the HuMAnS solution is only software and is not linked to any type of sensors or unit. It can be used, inter alia, for the analysis, modeling and monitoring of humanoid and human movement from a geometric model of the human body for constructing sensor measurements distributed over segments of the body. The HuMAnS solution implements a very simple Kalman filter, which diverges in the case of an AM fusion without gyroscope and only operates satisfactorily by using complete AGM units with 9 axes on each segment. In addition, said patent application does not disclose a measurement system for minimizing the consumption/performance cost ratio.